Upgrading heavy oil by visbreaking

ABSTRACT

Methods, systems and other embodiments associated with upgrading heavy oil by visbreaking are presented. A method of upgrading heavy oil includes mixing raw heavy oil with flue gases, CO2 and/or steam to produce a mixed heavy oil. This mixture is then heated to produce heated heavy oil. High pressure pulses are created in the heated heavy oil to crack the heated heavy oil to produce cracked oil with a lower viscosity than the heavy oil.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to systems and methods forreducing the density of heavy oils. More particularly, the systems andmethods relate to upgrading heavy hydrocarbon oils for transportation bypipeline from production fields to refineries for further processing.Specifically, the methods and systems of the present invention involvereducing the viscosity of the oil to allow for easier pumping andtransportation.

2. Background Information

One way to prepare heavy oil for transportation in a pipe is to add adiluent to the oil. This is done at blending stations where the diluentis added to meet pipeline specifications for both density and viscosity.A common diluent is naphtha, a light hydrocarbon with a typical AmericanPetroleum Institute (API) gravity of 60. The cost of naphtha is normallyat a premium because it is the light liquid fraction of crude oil atroom temperature. The cost of naphtha is normally 15 to 20% higher thanthe West Texas Intermediate (WTI) crude price. In addition to purchasingnaphtha, producers must transport it to their site and store it at thesite for later blending with heavy oil.

As the ability to easily extract conventional light and medium weightcrude oils declines, the increase in production of heavy oils hascreated a demand for diluent. The increase demand for diluent hassignificantly increased the cost of the diluent. The increased cost ofdiluent drives up the operating costs and this cost is passed on tocrude oil products.

To improve the pumping of heavy crude oil, a number of alternativemethods (e.g., processes) have been proposed for decreasing the densityof heavy oil. The primary alternatives proposed include visbreaking,deasphalting, coking and hydrocracking. In deasphalting, the heavyfraction, asphalt, is separated and removed. This is done by addedsolvents to the heavy oil to selectively precipitate the fraction ofasphalt from the other lighter fractions. The precipitation is performedin specially designed contact towers that operate at selective pressuresand temperatures.

In visbreaking, the heavy oil is thermally cracked. This is achieved athigh temperatures followed by a rapid quenching and settling. Thevisbreaking is limited to API gravity increments of 3 to 5 API. Thevisbreaking process requires high maintenance because a furnace used inthe visbreaking process often needs cleaned due to the buildup of coke,an undesirable product of visbreaking. High temperatures and pressuresused in the visbreaking process require costly equipment that can handlethe high temperatures and pressures.

Hydrocracking is the preferred process because it provides yields higherthan deasphalting and visbreaking. Hydrocracking adds hydrogen to theheavy oil and a catalyst at high pressures and temperatures. The highertemperature results in a higher conversion rate of heavy oil to upgradedoil. The better the mixing of the heavy oil, hydrogen and catalyst, thebetter the conversion rate and lower the residency time which results ina higher throughput.

However, these processes require a significant investment in equipmentthat may not be available at a producer's job site. Therefore, theseprocesses require the heavy crude to be transported to a refinerysuitable for upgrading the heavy crude by one of these processes. Theseprocesses require high pressures and temperatures. A high pressure plantrequires not only high pressure vessels but accessory equipment such aspumps, compressors, valves, as well as more energy for driving the highpressure pumps, compressors, and so on.

Conventional visbreaking or conventional deasphalting alone often doesnot provide sufficient viscosity reduction for all heavy crudes.Attempts to reduce the viscosity to a required level by these methodsusually lead to an incompatible two phase product from visbreaking andto a very low yield of deasphalted oil from deasphalting. A better wayof upgrading heavy oil is needed.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more preferred embodiments that illustrate the best mode(s) areset forth in the drawings and in the following description. The appendedclaims particularly and distinctly point out and set forth theinvention.

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate various example methods, and otherexample embodiments of various aspects of the invention. It will beappreciated that the illustrated element boundaries (e.g., boxes, groupsof boxes, or other shapes) in the figures represent one example of theboundaries. One of ordinary skill in the art will appreciate that insome examples one element may be designed as multiple elements or thatmultiple elements may be designed as one element. In some examples, anelement shown as an internal component of another element may beimplemented as an external component and vice versa. Furthermore,elements may not be drawn to scale.

FIG. 1 illustrates a first embodiment of a system for upgrading heavyoil.

FIGS. 2 and 3 illustrate a cavitation valve used in a second andpreferred embodiment for upgrading heavy oil.

FIG. 4 illustrates a first configuration of the second embodiment thatis a system for upgrading heavy oil that hydrocracks the heavy oil.

FIG. 5 illustrates a second configuration of the second embodiment thatis a system for upgrading heavy oil that deasphalts the heavy oil.

FIGS. 6A and 6B illustrate a third configuration of the secondembodiment that is a system for upgrading heavy oil that is anotherversion of a system that deasphalts the heavy oil.

FIG. 7 illustrates a fourth configuration of the second embodiment thatis a system for upgrading heavy oil that visbreaks the heavy oil.

FIG. 8 illustrates fifth configuration of the second embodiment that isa system for upgrading heavy oil that is another version of a systemthat visbreaks the heavy oil.

FIG. 9 illustrates a method of upgrading heavy oil.

FIG. 10 illustrates a more detailed variation of the method of upgradingheavy oil shown in FIG. 9.

FIGS. 11A-C illustrate three different configurations of the firstembodiment that are modular skid and/or truck mounted versions of thefirst embodiment of a system for upgrading heavy oil.

Similar numbers refer to similar parts throughout the drawings.

DETAILED DESCRIPTION

FIG. 1 illustrates a first embodiment of a system 10 used to upgradeheavy oil. The system 10 upgrades heavy oil to produce an oil that has alower viscosity and a lower density than the original oil. In the firstembodiment, the system 10 is comprised of a heater 2 (e.g., furnace) anda reaction chamber 4. The heater 2 may receive heavy oil from a storagetank 6 and prepare the heavy oil for cracking in the reaction chamber 4by heating the oil. The heater 2 may heat the heavy oil to anytemperature. However, in the first embodiment, the heater 2 isconfigured to heat the heavy oil up to about 450 degrees Celsius whichis a lower temperature than has been used in prior systems. In otherembodiments the system 10 may include a pump for pressurizing the heatedoil before it is pumped into the reaction chamber 4.

The reaction chamber 4 is configured to crack the heated heavy oil bysubjecting the heated heavy oil to pressure fluctuations. When the oilis subjected to significantly high pressure fluctuations, microscopicgas bubbles are created that expand and implode violently. The implodingmicroscopic bubbles raise the temperature at the interface of themicrobubbles and heavy oil. The temperature rise due to bubble collapsegenerates a localized extremely high cumulative amount of energy. Thisenergy enhances the cracking of the heated heavy oil because of theformation of radicals and cleavage of bonds. Cracking of the heatedheavy oil is generally the breaking of large hydrocarbon molecules intosmaller hydrocarbon molecules. The cracked oil can then be passed to apost processing system 8 to separate different petroleum fractions fromthe upgraded oil. The post processing system 8 may include towerseparators, overhead separators, heat exchangers, storage units andother devices to be discussed later.

As discussed below, the reaction chamber 4 may include a cavitationvalve configured to create high pressure differentials. The cavitationvalve can create a pressure differential of over 6000 psig which is amuch greater differential than is achieved by traditional systems ofupgrading heavy oil. This high pressure differential increases thequality of the upgraded oil produced by the system 10. Additionally, thecavitation valve operates under high pressure while the remainder of thesystem 10 can operate under lower pressures. In a traditional system,much more of the system for upgrading heavy oil is required to operateunder high pressure. A system with more components operating underhigher pressure require more expensive components that can handle highpressure and is therefore more costly than the system 10 of FIG. 1.Higher pressure components can require more maintenance due to thedifficulty of operating under high pressure. The system 10 of FIG. 1reduces maintenance costs because the reaction chamber 4 operates underhigh pressure while the remainder of the system 10 can operate at muchlower pressures.

Traditional systems and methods for upgrading require heavy oil to beheated and pressurized for 3 to 30 minutes before the heavy oil wascracked and upgraded. In the first embodiment, the heated heavy oil hasa residency time of one second or less in the reaction chamber 4. Inother embodiments, the residency time may be other less than twoseconds, less than three seconds or other residency times. The shorterresidency time translates into much smaller equipment needed to upgradeheavy oil for the same throughput capacity as a traditional process. Thesystem 10 of FIG. 1 also has a lower operating cost due to loweroperating pump pressures and a lower temperature in heater 2 incomparison to a traditional upgrading process. This translates intolower electrical and thermal energy requirements.

The system 10 may be mounted in a fixed location as a local refinery.Alternatively, the system 10 of FIG. 1 may be mounted on one or moreskids because the equipment of the system 10 has a small footprint andis much smaller than traditional systems for upgrading heavy oil. Thesystem 10 may be mounted on skids or trucks and brought to a remoteproduction field so that the heavy oil may be upgraded before the heavyoil is transported from the production field. For example, FIGS. 11A-Cshows a truck 1101 with the system 10 of FIG. 1 mounted on three skids1103, 1105 and 1107. The system 10 is shown as three units 1102, 1104and 1106 with one unit on one skid. The other details shown in FIGS.11A-C will be discussed later when discussing how the system 10 can bereconfigured. However, the system 10 may be mounted on a greater numberof skids or fewer than two skids. The system 10 may alternatively bemounted directly to one or more trucks or partially mounted on trucks,skids or other mounting surfaces. When the system 10 is mounted on twoor more skids or trucks, the system 10 is easily transported to a jobsite and easily assembled at the job site.

The system 10 is scalable and multiple components can be added to thesystem 10 to achieve the desired daily flow rates of a particularproducer of heavy oil. For example, the system 10 may be operated toprocess 250 barrels per day or the system 10 may be scaled to process100,000 barrels per day.

After the system 10 is assembled, the system 10 can be operated withless supervision than a traditional upgrading system requires. Forexample, the system 10 may include an American Petroleum Institute (API)density analyser 1121 (shown in FIGS. 11A-C) to automatically measurethe heavy oil density of oil input to the system 10. A computercontroller 1120 (shown in FIGS. 11A-C) of the system 10 will thenoptimize the temperature at which the heater 2 is to heat the heavy oil.The computer controller 1120 can also select the pressure fluctuationsthat the reaction chamber 4 is to subject the heated heavy oil to. Forexample, the computer controller 1120 can configure the reaction chamber4 to create pressure differentials between −2000 pounds per square inchgauge (psig) and 4000 psig and between 10 to 100 hertz. In anotherembodiment, the computer controller 1120 can also select the frequencyof the pressure fluctuations. For example, the computer controller 1120can control lengths of conduits feeding oil to a cavitation valvediscussed below to control the frequency of the pressure fluctuations.

In a second and preferred embodiment, the reaction chamber 4 comprises acavitation valve 26 as shown in FIG. 2. The cavitation valve 26 issimilar to the valve described in United States Patent Application No.2008/0256947. The reaction chamber 4 includes a first conduit 22 and asecond conduit 24 connected to the cavitation valve 26 configured tosupply heated heavy oil to the cavitation valve 26. The other ends ofthe first conduit 22 and the second conduit 24 are connected to a plenum20. The plenum 20 receives heated heavy oil from the heater 2 throughconduit 18.

The cavitation valve 26 includes a housing 27 which includes chambers 33and 34 connected to the first conduit 22 and the second conduit 24.Cavitation valve 26 has a movable valve member 36 configured toreciprocate longitudinally as indicated by arrow 29. The valve member 36has sealing members 38 and 40 in its ends. Sealing members 38 and 40 cansit against valve seats 42 and 44 respectively. The valve member 36 canmove between a first position, as shown in FIG. 2, in which fluid insecond conduit 24 can flow through cavitation valve 26 to an outputconduit 28 (while sealing member 38 bears against valve seat 42 andthereby prevents oil from the first conduit 22 from flowing to outputconduit 28). When the valve member 36 slides to a second position, asshown in FIG. 3, oil from the first conduit 22 can flow through thecavitation valve 26 to output conduit 28 while the flow of oil from thesecond conduit 24 to output conduit 28 is blocked by sealing member 40(which seals against valve seat 44).

In operation, heated heavy oil is received through conduit 18 into theplenum 20. In the preferred embodiment, the oil is pressurized withinthe plenum 20. The heated oil may be pressurized by pumping the oil fromthe heater 2 to the plenum 20 with a high-pressure pump. A centrifugalpump or another kind of pump may also be used to pump the heated oil tothe plenum 20 with high pressure. The pressure in plenum 20 causes theoil to flow down one of the conduits 22, 24. The initial position ofvalve member 36 determines which one of the conduits 22, 24 the oilflows through. If the valve member 36 is initially in the position shownin FIG. 2, oil will flow through the second conduit 24, through chamber34, between sealing member 40 and valve seat 44, and out through conduit28. When oil flows in this path, the flow of oil between valve member 40and valve seat 44 will tend to drive valve member 36 towards theposition shown in FIG. 3. When sealing member 40 contacts valve seat 44the flow of oil through conduit 24 is suddenly cut off. This creates a“water hammer” within conduit 24. The water hammer creates a very highpressure pulse which propagates through conduit 24 from the cavitationvalve 26 toward the plenum 20. In general, a water hammer is a pressuresurge that can arise in a pumping system pumping a fluid that undergoesan abrupt change in its rate of flow. An abrupt change of flow can becaused by a pump starting or stopping and also the opening or closing ofvalves such as when sealing member 40 contacts valve seat 44. Theseabrupt changes can cause all or part of a flowing water column in a pipe(conduit 24) to undergo a momentum change. This change can produce ashock wave that travels back and forth between the barrier that createdit and a secondary barrier. A water hammer conserves the energy of thepreviously moving water column by turning the water column velocityenergy into high pressure energy. Since fluids have a lowcompressibility, the resulting pressure energy can be very high. Thewater hammer phenomenon is well understood by those of ordinary skill inthe art. As discussed earlier, a high pressure pulse created by a waterhammer creates microbubbles of gas which implode to further raise thetemperature of the oil which results in the cracking of the oil into alower weight oil with a lower viscosity than the original heavy oil.

At the same time as valve member 36 moves to close sealing member 40against valve seat 44, sealing member 38 moves away from valve seat 42.This permits oil to flow from the first conduit 22 through cavitationvalve 26 to output conduit 28. In the meantime, the high pressure pulsewhich has been propagating upstream in the second conduit 24 eventuallyreaches plenum 20. At this point, some oil from second conduit 24 spillsinto plenum 20 and a corresponding low pressure pulse begins topropagate from plenum 20 toward the cavitation valve 26 along the secondconduit 24. When this low pressure pulse reaches chamber 34, it tends todraw valve member 36 back down into the position shown in FIG. 2. Thistendency is augmented by the tendency of oil flowing between sealingmember 38 and valve seat 42 to move valve member 36 in the samedirection.

The sudden closure of sealing member 38 against valve seat 42 causes awater hammer pulse to be propagated upstream in the first conduit 22. Itcan be appreciated that valve member 36 will reciprocate back and forth,alternately closing the fluid path from conduits 22 and 24. Aspreviously mentioned, in the preferred embodiment of system 10 thisfrequency is generally between 10-100 hertz. Each time valve member 36allows such an oil path to be opened and re-closed, a new water hammerpressure pulse (e.g., high pressure pulse) is generated. The frequencywith which these pressure pulses occur is determined primarily by thelengths of conduits 22 and 24, which are preferably equal in length.

The system 10 of upgrading heavy oil in FIG. 1 is reconfigurable. Thesystem 10 may, for example, be configured to upgrade heavy oil byhydrocracking, deasphalting, or visbreaking the heavy oil. Theseprocesses can be achieved in liquid/gas, liquid/liquid, liquid/slurry,and liquid/slurry/gas reactions. The preferred (second) embodiment forupgrading heavy oil can be implemented in at least five differentconfigurations. A first configuration for upgrading heavy oil byhydrocracking is shown in FIGS. 4 and 11A. A second configuration forupgrading heavy oil by deasphalting is shown in FIGS. 5 and 11B. Anotherconfiguration of upgrading heavy oil by deasphalting is shown as a thirdconfiguration in FIG. 6. A fourth configuration for upgrading heavy oilby visbreaking is shown in FIGS. 7 and 11C. Another configuration ofupgrading heavy oil by visbreaking is shown as a fifth configuration inFIG. 8. The modular nature of these configurations is discussed next andother details of these configurations are discussed later.

As mentioned earlier, the system 10 is shown mounted on a truck 1101 asa first unit 1102, a second unit 1104 and a third unit 1106. These unitsare mounted on corresponding skids 1103, 1105 and 1107. The first unit1102 may include a pump, a venturi, a mixer, and a heat exchanger. Thesedetailed components are not shown because they are not necessary to showhow the system 10 can be reconfigured in FIGS. 11A-C; however, thesecomponents are shown in detailed drawings discussed later. The secondunit 1104 may include the heat exchanger and a furnace. Unit 1106 mayinclude a tower separator and an overhead separator.

Some line (e.g., pipe) connections are common between the three units1102, 1104 and 1106 whether the system 10 is in the first, second,third, fourth or fifth configuration. These connections are generallymade after the truck 1101 arrives at the jobsite or after the units1102, 1104 and 1106 are offloaded from the truck 1101. For example, aninput line 1108 is attached to the first unit 1102 and connected to atank of heavy oil located at the jobsite. The pump in the first unit1102 pumps the oil from the tank into the first unit 1102. Another line1110 connects the venturi in the first unit 1102 to the heat exchangerin the second unit 1104. Line 1111 provides oil from the heat exchangerin the second unit 1104 to the tower separator in the third unit 1106.

In the first configuration for upgrading heavy oil by hydrocrackingshown in FIG. 11A, an additional line 1130 is added for adding recycledhydrogen from the third unit 1106 to the venturi in the first unit 1102.

In the second configuration for upgrading heavy oil, the heavy oil isupgraded by deasphalting as shown in FIG. 11B. In this figure, line 1142allows for the addition of condensates from the overhead separator inthe third unit 1106 to be added to oil in a line pressurized by the pumpin the first unit 1102. For example, a condensate stream of C₄ to C₈ canbe added through line 1142. Line 1144 in the second configuration allowsfor the addition of hydrocarbon gases from the overhead separator in thethird unit 1106 to heavy oil in the venturi in the first unit 1102. Inthe third configuration, heavy oil is also upgraded by deasphalting in asystem where the heavy is oil is upgraded in a two step process. First,a gaseous stream is mixed with the heavy oil and this mixture iscracked. Next, recovered condensates are mixed with the cracked oil tore-crack this mixture in a second stage of the third configuration toproduce upgraded oil.

In the fourth configuration, the heavy oil is upgraded by visbreaking asshown in FIG. 11C. In this figure, line 1150 allows for the addition ofcarbon dioxide, CO₂, to the heavy oil in the venturi in the first unit1102. Line 1152 also allows flue gases to be fed back from the furnacein the second unit 1104 to the heavy oil in the venturi in the firstunit 1102. In the fifth configuration heavy oil is also upgraded byvisbreaking. In this configuration, the heavy is oil is mixed with steamprior to coking and this mixture is then cracked.

In general, key components such as the heater 2, reaction chamber 4 andother elements remain the same between the hydrocracking, visbreakingand deasphalting configurations of cracking heavy oil. However, feedbackpaths within the system 10 may change between the differentconfigurations. Additionally, the mixing of the heavy oil with materialsuch as hydrogen, a catalyst, a solvent, CO₂, and other materials maychange depending on the process the system 10 is configured to use toupgrade heavy oil. However, as previously mentioned, the system 10 ofFIG. 1 has a small footprint so these modifications can easily be madewhen reconfiguring the system 10 between upgrading processes.Additionally, the computer controller 1120 can assist in reconfiguringthe system 10 to upgrade oil by a different process. For example, thecomputer can select a temperature for heater 2 and a pressure for thereaction chamber 4 based on the configurations of the system 10. Theseconfigurations and these processes will now be described in greaterdetail.

The details of the first configuration of the preferred (second)embodiment for upgrading heavy oil by hydrocracking the oil are shown asa system 400 in FIG. 4. In general, the system 400 upgrades heavy oil ina hydrocracking configuration by mixing hydrogen and a catalyst to theheavy oil and then cracking this heated oil in a cavitation valve usinghigh pressure pulses. The hydrocracking reactions are controlled by aset of variables such as: catalyst addition, hydrogen addition, furnaceoutlet temperature and controlled pressure at the cavitation valve. Ifthe operation is too severe, the resulting product becomes unstable andforms undesirable polymerisation products. The mild cracked mixture iscooled and separated into three streams: the overhead stream, theupgraded oil stream and the catalyst/bottoms steam. The overheadfraction is separated into gaseous and condensate streams. The gaseousstream supplies an external fuel gas system from which fuel gas isproduced. The condensate stream is fed back and added to the upgradedoil stream.

In more detail, the system 400 begins the hydrocracking of heavy oil byfeeding heavy oil in tank 401 through line 402 to pump 403. The pump 403pressurizes the heavy oil up to 1500 psi through line 404. The system400 adds a mixture of liquid catalyst and bottoms that is pumped throughline 431 to the heavy oil pumped through line 404. The system 400transports this mixture through a venturi 406 to create a vacuum. Thevacuum makes the mixture susceptible to the addition of hydrogen to themixture. The system 400 next adds recycled hydrogen received throughline 432 at the venturi 406. The system 400 transports the mixture ofheavy oil, liquid catalyst, bottoms and hydrogen through line 407 to astatic mixer vessel 408. After the mixture is mixed by the static mixervessel 408, the mixture exits through line 409 and is pre-heated in heatexchanger 410 to about degrees 375 Celsius. The system 400 transportsthe pre-heated mixture to a furnace 412 through line 411 for furtherheating up to degrees about 450 Celsius. A high pressure, hightemperature mixture exits the furnace 412 through line 413 and enters adistributor 414 (e.g., the plenum 20 discussed above). The distributor414 has two parallel lines 415, 416 (e.g., the first conduit 22 and thesecond conduit 24, discussed above) which provide for a continuous flowthrough cavitation valve 417. At the cavitation valve 417, a regulatorcontrols the valve aperture to control the induced cavitation pressure,which can be as high as 6000 psi at frequencies of 10 to 100 Hz. Theoscillation of pressure generated by the cavitation valve 417 formsmicrobubbles which grow and implode causing a substantial localized risein temperature for a short period of time at the interface between themicrobubbles, the catalyst, the hydrogen and the heavy oil. Thissubstantial rise in temperature promotes the formation of free radicalsand chemical reactions. These chemical reactions change the molecularstructure of the heavy oil by breaking large molecules into smallermolecules to reduce the viscosity and the specific gravity of the heavyoil.

The products of reaction exit the cavitation valve 417 through line 418and are fed back and cooled at heat exchanger 410 by the pre-heatingstream 409 before the pre-heating stream enters the furnace 412. Thesystem 400 transports the cooled products from the heat exchanger 410through line 419 to a separator 420. At the separator 420, theseproducts are flashed to generate three streams: an overhead stream, acatalyst/bottoms stream and an upgraded oil stream.

The upgraded oil stream in line 427 is the primary product output by thesystem 400. This product has a reduced viscosity and reduced gravitythat is more suited for transportation in pipes than the unprocessedheavy oil. The upgraded oil stream quality is controlled by fourvariables: the addition of liquid catalyst to the heavy oil, theaddition of hydrogen, furnace outlet temperature and control of inducedcavitation pressure.

The overhead stream exits the separator 420 through line 421 and thesystem 400 will cool this stream in a second heat exchanger 422. Thiscooled stream is transported by the system 400 through line 423 to anoverhead separator 424. The system 400 transports the non-condensablehydrocarbon gases from the overhead separator 424 through line 425 to afuel gas system. Condensate from the overhead separator 424 in line 426is added to the upgrading oil in line 427 and pumped to storage throughline 428.

The catalyst/bottoms stream exits the separator 420 through line 429 andis pressurized at pump 430. These pressurized catalyst/bottoms slurrytravel through line 431 and are recycled by mixing them with unprocessedheavy oil. The catalyst/bottoms stream is controlled by two variables:furnace outlet temperature and API density meter.

The configuration of system 400 in a mode of operation as shown in FIG.4 provides a wide range of operating variables not available intraditional hydrocracking and hydrotreating processes. For example, theconfiguration of FIG. 4 provides the ability to control online catalystaddition and concentration, the ability to control online operatingpressures by controlling induced cavitation pressures as well as theability to control temperature for chemical reactions with a lowresidence time. This allows the system 400 of FIG. 4 to respond rapidlyto desired operating conditions.

FIG. 5 illustrates in more detail a system 500 that implements thepreferred (second) embodiment in the second configuration of upgradingheavy oil by deasphalting the oil. In general, system 500 deasphaltsheavy oil by mixing condensates, non-condensables and heavy oil. Thismixture is heated at a controlled induced cavitation pressure to promotemild cracking and precipitation of asphaltenes from the heavy oil.

The system 500 is configured to store heavy oil in tank 501 and to heatthe heavy oil by a coil 502 to a temperature of about 35 to 45 degreesCelsius to make it pumpable. Heavy oil is typically defined as oil withan API gravity of less than 20. The heavy oil flows from tank 501through line 503 to pump 504. The pump 504 pressurizes the heavy oil to60 psi and pumps the pressurized oil through line 505. The system 500next mixes the pressurized oil in line 505 with condensates in line 546.For example, a condensate stream of C₄ to C₈ can be added through line546 and mixed with the heavy oil of line 505. This mixture is then fedthrough a venturi 507 to create a vacuum. The vacuum allows fornon-condensates to be added and mixed at the venturi 507. For example,hydrocarbon gases can be added from line 545 through the venturi 507.

The system 500 then sends the output of the venturi 507 to a staticmixer 509 via line 508. The mixture of heavy oil, condensate andhydrocarbon gases are fed through line 510 to high pressure pump 511 toraise the oil pressure up to about 1500 psi. The high pressure oil isthen pumped through line 512 to heat exchanger 513 where the mixture ispre-heated to about 275 degrees Celsius. The system 500 sends the highpressure, pre-heated mixture through line 514 to a furnace 515 where itstemperature is raised up to about 450 degrees Celsius. The highpressure, heated mixture exits the furnace 515 and travels through line516 to a plenum 517. Two parallel lines 518 and 519 carry the mixture toa cavitation valve 520 where the oil is cracked with high pressuredifferentials.

At the cavitation valve 520, a regulator controls the valve aperture tocontrol the induced cavitation pressure, which can be as high as 6000psi at frequencies of 10 to 100 Hz. An oscillating pressure generated bythe cavitation valve 520 forms microbubbles which grow and implode. Theimplosions cause a substantial localized rise in temperature for a shortperiod of time at the interface between the microbubbles and heavy oil.This substantial rise in temperature promotes the formation of freeradicals and chemical reactions. These chemical reactions change themolecular structure of the heavy oil reducing the viscosity and thespecific gravity.

The oil products of reaction exit the cavitation valve 520 and thesystem 500 transports these products through line 521 to a reboiler 522where they are cooled. The cooled oil exits the reboiler 522 throughline 523 and proceeds to a tower separator 524. The oil is flashed inthe tower separator 524 to generate three streams: a gaseous stream, aliquid stream and a bottoms fraction stream.

The system 500 is configured to mix the liquid stream that exits thetower separator 524 through line 541 with condensate received from line540. This mixture is a deasphalted output from the system 500 that isready for pipeline transmission or may be sent to storage. The system500 pressurizes the bottoms fraction after it exits tower separator 524through line 525 with a pump 526. The system 500 is configured totransport the pressurized bottoms fraction through line 527 and intoline 528 for feedback into the reboiler 522 to control the asphaltconcentration. Another portion of the bottoms fraction is fed back intothe heat exchanger 513 through line 529 so that it is cooled bypre-heating the heavy oil mixture. This cooled stream exits heatexchanger 513 through line 30 and proceeds to asphalt storage.

The gaseous stream exits the tower separator 524 through line 532 and iscooled in heat exchanger 533. The cooled stream exits the heat exchangerthrough line 534 and enters an overhead separator 535. Non-condensablehydrocarbon gases exit the overhead separator 535 through line 543 andare fed back to the venturi 507 via supply line 545. The system 500feeds a portion of the non-condensable hydrocarbon gases from theoverhead separator 535 through line 544 to a fuel gas system forconversion to combustion fuel.

A condensate stream travels from overhead separator 535 through line 536to a pump 537 where it is pressurized. The pressurized output in supplyline 538 supplies three streams (lines): line 546 for feedback into thedeasphalting portion of the system 500, line 539 for reflux into thetower separator 524, and line 540 as an addition to the deasphalted oilproduct in line 541 that is ready for pipeline transmission through line542.

FIG. 6 illustrates the preferred (second) embodiment in the thirdconfiguration for upgrading heavy oil. The third configuration operatesas a system 600 that upgrades heavy oil by another variation ofdeasphalting the heavy oil. In the third configuration, the system 600deasphalts heavy oil in a two step cracking process. The system 600 isconfigured to crack heated heavy oil mixed with a gaseous stream with afirst cavitation valve. The mildly cracked heavy oil is cooled and fedinto separators and a separated gaseous stream is cooled and routed to afuel gas system. The system 600 pumps and mixes recovered condensates ofan overhead separator with the bottoms fractions of a separation tower.This mixture is again heated and then cracked by a second cavitationvalve. The system 600 is configured with a second group of separators toseparate the cracked heavy oil into deasphalted oil ready for pipelinetransportation or storage and into a gaseous stream to supply a fuel gassystem.

In more detail the system 600 is configured to feed heavy oil from tank699 through line 601 into a pump 602. The pump 602 pressurizes the heavyoil in line 603 up to about 1500 psi. The system 600 sends thispressurized heavy oil through a venturi 604 where hydrocarbon gases C₁to C₃ are added from line 625 and then the oil flows through line 605into a mixer vessel 606. The system 600 transports the mixture of heavyoil and hydrocarbon gases through line 607 to a heat exchanger 608 forpre-heating up to about 375 degrees Celsius. The heated mixture thentravels through line 609 into a furnace 610 for further heating up toabout 450 degrees Celsius.

The system 600 transports the cracked products of reaction through line616 back to the heat exchanger 608 for cooling by pre-heating stream607. These cooled products of the reaction stream exit the heatexchanger 608 through line 617 and proceed to a tower separator 618. Theproducts of reaction are flashed at the tower separator 618 to generatetwo streams: a gaseous stream and a bottom's stream.

The system 600 transports the gaseous stream from the tower separator618 through line 620 to a heat exchanger 621 for cooling. This cooledgaseous stream enters an overhead separator 623 through line 622. Thenon-condensable hydrocarbon gases exit the overhead separator 623through line 624 and split into two streams. The first stream travelsthrough line 625 and is mixed with the heavy oil at the venturi 604. Thesecond stream travels through line 626 to a fuel gas system. Thecondensable hydrocarbons travel from the overhead separator 623, throughline 627 and enter a pump 628. The pressurized hydrocarbons exit thepump 628 through line 629 which splits into three streams. The firststream travels through line 630 and is fed back to the tower separator618 as a reflux stream to control the overhead temperature of the towerseparator 618. A second stream of C₄ to C₈ condensate travels throughline 631 and is injected into a second venturi 635 which initiatespreparing the oil for further cracking at second cavitation valve 646. Athird stream exits from pump 629 through line 674 and is added to thedeasphalted oil product in line 666 that is ready for storage.

The system 600 sends the bottoms fraction of the tower separator 618through line 632 to pump 633. The pressurized bottoms fraction travelsthrough line 634 to the second venturi 635. As previously mentioned, atthe second venturi 635 a condensate of C₄ to C₈ is added to the bottomsfraction. The system transports this mixture through line 636 to a mixervessel 637. The mixture is pre-heated in another heat exchanger 639 upto about 375 degrees Celsius. The heated mixture enters a furnace 641via line 640 where it is heated up to about 450 degrees Celsius. Thehigh pressure/high temperature mixture exits the furnace 641 throughline 642 and enters a plenum 643 of the second cavitation valve 646. Theplenum 643 transports the mixture over two parallel lines 644 and 645 toprovide for a continuous flow through the second cavitation valve 646.

The system 600 controls the cavitation valve 646 to create pressurepulses in a way similar to the cavitation valves discussed earlier. Thesystem 600 transports cracked products of the second cavitation valve646 through line 647 to a reboiler 648 where they are cooled. The cooledproducts exit the reboiler 648 through line 649 and proceed to a towerseparator 650. The products of reaction are flashed in the separationtower 650 to generate three streams: a gaseous stream, a liquid streamand a bottoms fraction.

The system 600 transports the gaseous stream from the separation tower650 through line 651 to a heat exchanger 652. The gaseous stream iscooled at the heat exchanger 652 before it passes through line 654 toenter an overhead separator 655.

The liquid stream (e.g., upgraded deasphalted oil) exits tower separator650 through line 663 and proceeds to pump 664. The system 600 combinesthe pumped and upgraded deasphalted oil in line 665 with condensatestream 662. The combined mixture of upgraded oil is then output throughline 666 ready for pipeline transportation or for storage.

The system 600 transports the bottoms fraction to the tower separator650 through line 667 to pressuring pump 668. This stream exits the pump668 on line 263, which splits into line 670 and line 672. Line 670 feedsreboiler 648 to control the asphalt concentration. The oil in line 672is cooled by pre-heating the heavy oil condensate stream mixture at heatexchanger 639. The cooled stream exits heat exchanger 639 through line673 and proceeds to asphalt storage.

The system 600 transports the non-condensable hydrocarbon gases from theoverhead separator 655 on line 657 to a fuel gas system (external thesystem of FIG. 6) for producing combustion fuel. Condensate exits theoverhead separator 655 through line 656 which feeds a pump 659. Thepressurized condensate travels through line 660 to supply line 661 andsupply line 662. The condensate in line 661 supplies reflux to theseparation tower 650. The condensate in line 662 is added to thedeasphalted oil product before it is transported over a pipeline orstored.

In summary, the system 600 of FIG. 6 provides another configuration forallowing for deasphalting at different operating conditions in twostages. In the first stage heavy oil is cracked with a gaseous solvent.In the second stage, the oil is further cracked using a mixture ofliquid solvents. The system 600 controls the composition of both gaseousand liquid solvents by controlling process operating conditions. Thisprocess provides several variables to allow an operator of the system600 to meet a deasphalted product specification.

The fourth configuration of the preferred (second) embodiment is shownin more detail in FIG. 7. In the fourth configuration, the preferredembodiment is configured as a system 700. The system 700 visbreaks theheavy oil to reduce the viscosity and density of the heavy oil. Oil withreduced viscosity and density can be transported by pipeline fromproduction fields to refineries for further processing. In general, thesystem 700 upgrades heavy oil by mixing a stream of heavy hydrocarbonoil with CO₂, flue gases and/or steam. The CO₂ and flue gases aid in thecracking of large heavy oil molecules into smaller molecules. Thismixture is heated under pressure and passed through a cavitation valveto induce cavitation at a controlled pressure and frequency to reducethe viscosity and density of the heavy hydrocarbon oil. This system 700of visbreaking heavy oil produces fuel gas and a product with lowerviscosity and a lower density than the original heavy oil.

In more detail, the system 700 begins the visbreaking of heavy oil bypumping oil from tank 701 through line 702 with pump 703. The pump 703pressurizes the heavy oil up to about 1500 psi through line 704. Thepressurized oil is passed through a venturi 705. Flue gases from line734 and/or CO₂ from line 735 are added from line 736 to the heavy oil atventuri 705. The system 700 next feeds the heavy oil mixture fromventuri 705 through line 706 into a mixer vessel 707. The mixturetravels through line 708 to a heat exchanger 709. The system 700pre-heats the mixture in a heat exchanger 709 to up to about 375 degreesCelsius. A furnace 711 further heats the heavy oil mixture up to about450 degrees Celsius.

Next, the high pressure/high temperature mixture exits the furnace 711through line 712 and enters a plenum 713. The system feeds this mixturefrom the plenum 713 through two parallel lines 714 and 715 to acavitation valve 716. The two parallel lines 714 and 715 provide acontinuous flow supply of the oil mixture to the cavitation valve 716.As discussed earlier, the cavitation valve 716 creates high pressurepulses that can be at frequencies of 10 to 100 Hz. At the cavitationvalve 716 a regulator controls a cavitation valve aperture to controlthe induced cavitation pressure, which can be as high as 6000 psi. Theoscillation in pressure generated by the cavitation valve 716 formsmicrobubbles which grow and implode causing a substantial localized risein temperature for a short period of time at the interface between themicrobubbles and heavy oil. This substantial rise in temperaturepromotes the formation of free radicals and chemical reactions. Thesechemical reactions change the molecular structure of the heavy oil,reducing the viscosity and the specific gravity of the heavy oil.Additionally, a system 700 with a cavitation valve 716 can takeadvantage of the acidic properties of flue gases and the solventproperties of CO₂ when visbreaking heavy oil to enhance the mildcracking conditions created by the cavitation valve 716.

The system 700 next transports products of the reaction in thecavitation valve 716 through line 717 back to the heat exchanger 709 topre-heat heavy oil in line 708 that has not yet been heated. The cooledproducts next exit the heat exchanger 709 and travel through line 718 sothat different hydrocarbon products can be separated. A separator tower719 receives the cool products from line 718 and generates a gaseousstream and a bottoms stream. The bottoms stream travels through line 730and is fed to pump 731 where it is pressurized. The pressurized bottomsstream in line 732 is added to condensate in line 729 to generateupgraded oil in line 733 that is ready for pipeline transportation.Alternatively, the upgraded oil in line 733 can be sent to a storagetank.

The gaseous stream exits the separator tower 719 through line 720. Thisstream is cooled in a second heat exchanger 721 and is passed throughline 722 to an overhead separator 723. Non-condensable hydrocarbon gasesexit the overhead separator 723 through line 725 and may be provided toa fuel gas system. A second stream of the overhead separator 723, thecondensate stream in line 724, is pumped by a pump 726. This stream ispumped through line 727. Line 727 feeds line 728 that supplies a refluxstream to control the tower separator's 719 overhead temperature. Line727 also feeds 729 that is added to line 732. As previously mentioned,the upgraded oil in line 733 is a combined product of lines 729 and 732that is ready for pipeline transportation.

The preferred (second) embodiment may also be converted to the fifthconfiguration of the preferred embodiment as shown in FIG. 8. In thefifth configuration, the preferred embodiment operates as a system 800to upgrade heavy oil by another version of visbreaking heavy oil. Thisvariation of visbreaking uses steam as a precursor to coking. Addingsteam to the heavy oil improves the mild cracking conditions within acavitation valve. The system 800 begins to upgrade heavy oil by heatingit in tank 701 by with a coil 835 to a temperature of about 35 to 45degrees Celsius. The heated heavy oil proceeds to venturi 705 similar tothe venturi in FIG. 7. Instead of adding CO₂ or flue gases as in system700, steam is added from line 834 to the heavy oil in the venturi 705.The system 800 is configured to process the heavy oil and steam fromhere on in a way similar to the system 700 of FIG. 7.

Example methods may be better appreciated with reference to flowdiagrams. While for purposes of simplicity of explanation, theillustrated methodologies are shown and described as a series of blocks,it is to be appreciated that the methodologies are not limited by theorder of the blocks, as some blocks can occur in different orders and/orconcurrently with other blocks from that shown and described. Moreover,less than all the illustrated blocks may be required to implement anexample methodology. Blocks may be combined or separated into multiplecomponents. Furthermore, additional and/or alternative methodologies canemploy additional, not illustrated blocks.

FIG. 9 illustrates a method 900 of upgrading heavy oil by visbreaking.The method 900 mixes raw heavy oil with flue gases, CO₂ and/or steam, at902, to produce mixed heavy oil. This mixture is heated, at 904, toproduce heated heavy oil. High pressure pulses are created in the heatedheavy oil, at 906, to crack the heated heavy oil. This produces oil witha lower viscosity than the heavy oil. The high pressure pulses createmicroscopic bubbles in the heated heavy oil. The microscopic bubblesexpand and implode to form radicals and cleavage of bonds to facilitatecracking the heated heavy oil. As discussed earlier, a cavitation valvecan be used to create the high pressure pulses. For example, a hammermember within a cavitation valve may oscillate back and forth betweentwo positions to create the high pressure pulses. The high pressurepulses can be created based, at least in part, on a piston sliding backand forth in the cavitation valve.

FIG. 10 illustrates a method 1000 associated with upgrading heavy oilthat is a variation of method 900 in FIG. 9. The method 1000 begins bypumping raw heavy oil at a pressure of about 1500 pounds per square inch(psi), at 1002. Similar to method 900, the raw heavy oil is mixed withflue gases, CO₂ and/or steam, at 1004, to produce mixed heavy oil. Thismixture is preheated, at 1006. The preheating may occur in a preheaterwhere it is preheated to about 375 degrees Celsius. The preheated heavyoil is then heated in a furnace, at 1008. The furnace may heat the heavyoil to about 450 degrees Celsius. High pressure pulses are created inthe heated heavy oil, at 1010, to crack the heated heavy oil.

The cracked oil is separated into an overhead stream, a bottoms streamand an upgraded oil stream, at 1012. The high pressure pulses can becreated by a cavitation valve so that the high pressure pulses changepressure from about −2000 pounds per square inch gauge (psig) to about4000 psig and the high pressure pulses can have a frequency in a rangeof 10-100 hertz. The residency time of the heated heavy oil in thecavitation valve can be less than one second, two seconds or anothervalue.

In the foregoing description, certain terms have been used for brevity,clearness, and understanding. No unnecessary limitations are to beimplied therefrom beyond the requirement of the prior art because suchterms are used for descriptive purposes and are intended to be broadlyconstrued. Therefore, the invention is not limited to the specificdetails, the representative embodiments, and illustrative examples shownand described. Thus, this application is intended to embracealterations, modifications, and variations that fall within the scope ofthe appended claims.

Moreover, the description and illustration of the invention is anexample and the invention is not limited to the exact details shown ordescribed. References to “the preferred embodiment”, “an embodiment”,“one example”, “an example”, and so on, indicate that the embodiment(s)or example(s) so described may include a particular feature, structure,characteristic, property, element, or limitation, but that not everyembodiment or example necessarily includes that particular feature,structure, characteristic, property, element or limitation. Furthermore,repeated use of the phrase “in the preferred embodiment” does notnecessarily refer to the same embodiment, though it may.

1. A method of upgrading heavy oil by visbreaking comprising: mixing rawheavy oil with at least one of the group of: flue gases, CO2 and steamto produce a mixed heavy oil; heating the mixed heavy oil to produceheated heavy oil; and creating high pressure pulses in the heated heavyoil to crack the heated heavy oil to produce cracked oil with a lowerviscosity than the heavy oil.
 2. The method of claim 1 wherein the stepof heating the mixed heavy oil further comprises: heating the mixedheavy oil in a furnace to about 450 degrees Celsius.
 3. The method ofclaim 2 further comprising: preheating the mixed heavy oil in apreheater to about 375 degrees Celsius prior to the step of heating themixed heavy oil in the furnace.
 4. The method of claim 1 wherein thestep of mixing raw heavy oil is performed in a mixer vessel.
 5. Themethod of claim 1 wherein the step of mixing raw heavy oil furthercomprises: creating a vacuum with a venturi, wherein the step of mixingis performed in the venturi.
 6. The method of claim 1 furthercomprising: separating the cracked oil into an overhead stream, abottoms stream and an upgraded oil stream.
 7. The method of claim 1further comprising: pumping the raw heavy oil at a pressure of about1500 pounds per square inch (psi); and wherein the step of mixing isperformed in a venturi.
 8. The method of claim 1 wherein the step ofcreating high pressure pulses further comprises: creating the highpressure pulses in a cavitation valve.
 9. The method of claim 8, whereinthe step of the creating high pressure pulses is generated by fluidhammering action in the cavitation valve.
 10. The method of claim 8wherein the residency time of the heated heavy oil in the cavitationvalve is less than three seconds.
 11. The method of claim 8 wherein theresidency time of the heated heavy oil in the cavitation valve is lessthan one second.
 12. The method of claim 1 further comprising: creatingthe high pressure pulses that change pressure from about −2000 poundsper square inch gauge (psig) to about 4000 psig, wherein the highpressure pulses have a frequency in a range of 10-100 hertz.
 13. Asystem for upgrading heavy oil by visbreaking comprising: a mixer to mixat least one of the group of: flue gases, CO2 and steam with raw heavyoil to produce mixed heavy oil; a furnace to heat the mixed heavy oil tocreate heated heavy oil; and a reaction chamber configured to receivethe heated heavy oil and to generate a controlled cavitation with highpressure differentials to facilitate the local cracking of the heatedheavy oil to produce cracked oil that has a lower viscosity than theheated heavy oil.
 14. The system of claim 13, further comprising: a heatexchanger to preheat the mixed heavy oil before it enters the furnace,wherein the cracked oil is circulated through the heat exchanger topreheat the mixed heavy oil.
 15. The system of claim 13, furthercomprising: a separator configured to separate the cracked oil into anoverhead stream, a bottoms stream and an upgraded oil stream.
 16. Thesystem of claim 13, further comprising: a heat exchanger to cool theoverhead stream to produce a cool overhead stream; and an overheadseparator to separate the cool overhead stream into a non-condensablehydrocarbon gases and a condensate stream.
 17. The system of claim 13,wherein the mixer is a venturi that creates a vacuum.
 18. The system ofclaim 13 wherein the reaction chamber is a cavitation valve.
 19. Thesystem of claim 18, further comprising: a piston within the cavitationvalve, wherein the high pressure differentials are created, at least inpart, by a back-and-forth action of the piston.
 20. The system of claim13, wherein the residency time of the heated heavy oil in the reactionchamber is less than three seconds.
 21. The system of claim 13, whereinthe residency time of the heated heavy oil in the reaction chamber isless than one second.
 22. The system of claim 13, wherein the heater isconfigured to heat the heavy oil to about 450 degrees Celsius, andwherein the reaction chamber is configured to create pressuredifferentials between −2000 psig and 4000 psig and between 10 to 100hertz.